Over the years, laser eye surgery systems have replaced manual surgical tools in ophthalmic procedures. Indeed, with applications in a variety of different procedures, laser surgery systems have become ubiquitous in ophthalmic surgery.
For example, in the well-known procedure known as LASIK (laser-assisted in situ keratomileusis), a laser eye surgery system employing ultraviolet radiation is used for ablating and reshaping the anterior surface of the cornea to correct a refractive condition, such as myopia or hyperopia. Further, prior to ablation during LASIK, the cornea is incised with a laser eye surgery system employing a non-ultraviolet, ultra-short pulsed laser beam to create a flap to expose an underlying portion of the cornea so that it can be then be ablated and reshaped with ultraviolet laser beams. Afterwards, the treated portion is covered with the flap.
More recently, laser eye surgery systems have been developed for cataract procedures. These systems can be used for various surgical procedures, including for instance: (1) creating one or more incisions in the cornea or in the limbus to reshape the cornea, (2) creating one or more incisions in the cornea to provide access for a cataract surgery instrument and/or to provide access for implantation of an intraocular lens, (3) incising the anterior lens capsule (anterior capsulotomy) to provide access for removing a cataractous lens, (4) segmenting and/or fragmenting a cataractous lens, and/or (5) incising the posterior lens capsule (posterior capsulotomy) for various cataract-related procedures.
With capsulotomy, the surgeon creates a circular opening in the lens capsule, which is a cellophane-like bag that holds the lens. The incision to create this circular opening is one of the most critical steps of the cataract procedure as its size, shape, and centering may impact the effective positioning of an artificial intraocular lens (IOL) following removal of the cataractous lens. If the artificial lens becomes de-centered or shifts back or forward by even a slight degree, its performance may be diminished leading to refractive error. Laser eye surgery systems for cataract procedures therefore often include imaging systems for more accurate and precise placement of incisions and capsulotomy.
Sometimes, however, to reduce the possibilities of incomplete cutting, a capsulotomy may take longer to perform than is ideal, especially when the scan patterns are substantially longer in a depth dimension than the capsule. Further, slight eye movement and/or lens capsule movement may increase the possibility of an inadequate capsule incision. Hence, laser surgery systems with improved characteristics for intraocular target identification and incision, and related methods, would be beneficial.